1. Field of the Invention
The present invention relates to a method for controlling the thicknesses of webs and flanges of beam sections in universal rolling mill stands by means of gage-meter circuits provided for the horizontal rolls and the vertical rolls. The present invention also relates to an arrangement for carrying out this method.
2. Description of the Related Art
It has been found in rolling sections, for example, I-sections, that deviations occur in the thicknesses of the webs and/or flanges of the sections. These deviations may be long-time deviations caused, for example, by the continuously occurring wear of the rolls or by temperature-related expansions of the rolls. The deviations may also be short-time deviations caused, for example, by temperature variations or by differences in the material in the section to be rolled.
In the past, it was attempted to eliminate the deviations by position-controlled mechanical adjustments. However, mechanical adjustments did not result in substantial progress because this type of adjustment operates very slowly and inaccurately, so that it was hardly possible to counteract the short-time deviations.
In addition, when the I-sections are rolled, the elongation of the web is to be 2 to 4% greater than the elongation of the flanges. When the above-mentioned known controls were used, it was easily possible that the differences in length were smaller or greater than required, and, thus, departed from the tolerance range, which created instabilities in sections.
It has also been attempted to use gage-meter controls which were known from strip rolling. However, in this method, mechanical adjustments were also used, so that the deviations which were recognized could not be eliminated quickly enough. This method also caused deviations from the required differences in length of the web and flanges.
It is, therefore, the primary object of the present invention to provide a method for the optimum compensation of the thicknesses of webs and flanges. Also, an arrangement for carrying out this method is to be provided.